VSZ, the virtual memory size, references all of the memory that an individual process can access, including swapped memory. This is the memory size that is allocated during the initial execution of the program. VSZ is reported in KiB.
RSS, the resident set size, references how much memory a particular process has allocated in RAM, not including swapped memory. RSS includes shared library memory as long as that memory is currently available. RSS also includes stack and heap memory. RSS memory can be larger than the total memory available in the system based on the fact that these memory references are often shared. RSS is reported in kilobytes.
When we start up a simple HTTP server, we can see the VSZ and RSS that are ...
